The recycling of aluminum frequently involves the use of rotary furnaces. Typically, aluminum scrap and/or used aluminum products are received in a rotary furnace for melting. When melting is complete, the molten aluminum is discharged from the rotary furnace for further processing.
More specifically, rotary furnaces of the type utilized in aluminum recycling comprise a large drum which is supported for rotation about a longitudinal axis. One end of the drum is closed with the other end of the drum being normally closed by a door. At the start of each operating cycle, the drum is tilted upwardly for charging with aluminum to be melted. The drum is tilted downwardly into a horizontal orientation and the door is closed. The temperature within the drum is then raised sufficiently to melt the aluminum received therein. After the aluminum is melted, the drum is tilted downwardly to discharge the aluminum for further processing.
Heretofore, the doors used to close rotary furnaces during the melting of aluminum received therein have been supported independently from the drum of the furnace. This means that the door must be fully opened both during the charging of the drum with aluminum to be melted and during the discharge of the aluminum from the drum. The requirement of fully opening the drum to effect discharge of molten aluminum therefrom is disadvantageous because it allows the drum to cool thereby requiring substantial reheating for the next operating cycle.
The present invention comprises an improvement during construction for rotary furnaces which overcomes the foregoing and other difficulties which have long characterized the prior art. In accordance with the broader aspects of the invention, a rotary furnace is provided with a door which is supported for pivotal movement with the drum between its upwardly inclined charging orientation, its horizontal melting orientation, and its downwardly inclined discharging orientation. Because the door pivots with the drum, it is not necessary to fully open the door in order to discharge molten aluminum therefrom. Rather, the lower portion of the door is separately openable to permit discharging of molten aluminum, thereby retaining heat within the drum.
In accordance with more specific aspects of the invention, a rotary furnace includes a drum that is supported on a frame for pivotal movement between an upwardly inclined charging orientation, a horizontal melting orientation, and a downwardly inclined discharge orientation. A door for the drum is mounted on the same frame as the drum for pivotal movement therewith. The door is fully openable to facilitate charging of the drum with aluminum to be melted. The door includes a pour door comprising the lower portion thereof which is separately openable to facilitate the discharge of molten aluminum from the drum.
The door of the present invention further includes apparatus for heating the interior of the drum to melt the aluminum contained therein. Typically, the heating apparatus comprises a burner fueled by natural gas, however, other heating apparatus may be utilized in the practice of the invention. The heating apparatus is operated not only during the melting of the aluminum received in the drum, but also during the discharge of molten aluminum from the drum so that the interior of the drum is not significantly cooled during the discharging of the aluminum. In this manner the operational efficiency of rotary furnaces incorporating the door of the present invention is substantially increased.